This invention concerns a process for preparing thioethers of mercapto-carboxylic acids by contacting glycolic acid or bromoacetic acid and a mercaptan in the presence of aqueous hydrogen bromide.
Thioethers of mercapto-carboxylic acids, especially of mercaptoacetic acid, have been prepared and studied previously. The salts and esters of the long-chain alkyl ethers have been found useful as wetting agents, emulsifiers and thickeners for aqueous products. British patent 941,300 describes the use of such compounds as thickeners and the like.
Thioethers of mercaptoacids are generally formed by treating a sodium mercaptide with the sodium salt of a chloroacid, or by addition of an unsaturated compound to the mercaptoacid. E. E. Reid, Organic Chemistry of Bivalent Sulfur, Vol. 3, Chemical Publishing Co., Inc., New York, 1960, Chapter 3, thoroughly discusses the preparation and use of thioethers of mercapto-carboxylic acid by such methods. The mercapto acids can be prepared by the reaction of sodium hydrosulfide with sodium chloroacid in an aqueous medium.